Right rear brake light went out, replaced (p21 5w) a lot of corrosion when the old bulb was removed, cleaned up and put in the new, the parking light portion of the bulb works but the brake filament still does not --- any suggestions on what to try now, the left rear works fine.

 

Try another bulb, or you can just switch the other bulb that's working to see if it's the connection.

 

a lot of corrosion when the old bulb was removed, cleaned up and put in the new, the parking light portion of the bulb works but the brake filament still does not --- any suggestions on what to try now

go back and clean more. the two parts of the bulb have sep' power connections .... I suspect you got one clean (plus the common ground) but not the other. You may be able to finish the job ....

but open question is where is water getting in to cause the corrosion???? This is the real problem you need to fix.

 

Judging from your signature you have a sunroof. This is where your water is coming in from. ALL sunroofs will leak over time. Or from the taillight housing gasket. Worst case scenario, the body control unit 1 is failing. Best case scenario, you have the bulb in backwards. I believe that that bulb has offset pins on the side. It will cram in the wrong way.

 

Thanks for the replies, noticed last fall that some condensation would collect in that tail light, so pretty sure it is seal on the light -- bulb is in correctly -- as soon as it stops raining here, I'll try and clean it out some more and try a little spray electrical contact cleaner.